Ring oscillator pulse producing circuit



H. GALLAY 2,642,526

RING OSCILLATOR PULSE PRODUCING .CIRCUIT 2 Sheets-Sheet 1 INVENTORHARP/S GflLl/YY BY U ATTORNEY L L. 9% L J l A A. A

VIII! llll June 16, 1953 Filed Dec. 19. 1949 June 16, 1953 v GALLAY2,642,526

RING OSCILLATOR PULSE PRODUCING CIRCUIT Filed Dec. 19. 1949 4 2Sheets-Sheet 2 TIME- INVENTOR H14 REVS GWZZA Y ATTORNEY pacitive andresistive coupling: :islu'sed between successive tubes-with theyMuesnfitherresistors Patented June 16, 1953 ucri-isicallayfinei evnlNfl 'assignortcrederal Telecommunication Laboratories, 1110., if-NewYork, N. -Y.,t*a;?corporation aff nlaware iApplicatfonnecember 19,19.49,seramoi1s3.s&3

This=invention relat s- -to ring aOSQiHatOIE-PHISB producing circuitsand. more particularly to. oscillators in "Wh'iOhuL SBIiGS Of electrondischarge devices are caused=sequentially-to-.-opcra e, either as a freerunning oscillatoror-iasiasynchronized oscillator.

Various types of ring' oscillatorscin"which a a series of tubes -are-.soconnected 1 that :they :are

operated in sequence have heretofore been=-proposed. Inrgener-al:such-circuits are: usually'made of' electron discharge devicesso:connected that upon cessation of= operation :of one devicea voltage isapplied. to-the next ssucceeding device -to render it operative. suchsys-tems as devised in the past considerable complications' have ibeenintroduced in the circuits :to :assure-that only one discharge devicew-illbe triggerediinto operation at a time.-Moreover,vwhensynchronisation is required, considerable -care-"must :beexercised to assure that this :is.properly accomplished.

Furthermore, insystemswof this-nature-Jtis generally quite difficulttoeassure athat-lthec-discharge devices operate for aggivencfixedperiodof time. Usually if. pulse :outputs a-re :desired. it is necessary toshape the output energy to.- secure pulses of constant durationand:repetition frequency.

I It is an objectof this-invention iiOSDI'OVide a simple circuit of thering oscillator type inwh-ich only' one ofthe discharge. devices mayroperate at a time.

it is a further-object-of :this-:invention tonprovide a ringoscillatoriin whichthe separatezoutput pulses of the several electrondischarge-devices' are each of precise timeduration: and repetitionrates.

According to afeatureof: this invention .=the operation of only a singleelectron' dischargedevice or tube of the ring oscillator is assuredi byproviding a current limiter idevicezin-series with "40 acommon anode andcathodecircuit ofthesystern, adjusted so that the currentlisi sufficient-to maintain-only one-ofthe tubes conductive.

. "According to another feature? ofc thet'device caand capacitors sochosen that a'ifixed timeifc'onstant in excess"of --the':duration of-.op'eration is maintained. Suchen oscillator. may be brought intosynchronism byi periodici-pu1ses:. appliedsto" :the a common cathodecircuit, for example,--.once

for each pulse. Alternatively,...synchronizing.

.- pulses derived from anos'cill'atonhavinga period less than the normaltiming of the time constant utcnims. (enact-:27)

. mzing puises "to apply Ito .the commo ca od circuit ito :assuregenerationaof pulseslhavilig a .precise 'rti-me .duration correspondingwith 5111 spacinglcfithe-synchronizin ;.pillses. TfIhe .jabove-mentioneid arid .otherffeatures and objects of Zthisiinvention.arid'the manner ,of iat- -taining "them Wilhhecome more apparent andthe invention? itself Willibeibst .understoddglgy reference .to" the.following; idescrintionsof.v an. em-

9 T ibo'dimentiof f thejsinventionltaken. in'..conjun ctio withthesaccompanying.idrawings, wherein:

.i-Eigl 1 isa schematic circuit tdia ramm. jlii i oscillatorscircuitiinlaccofidance withgtheiinvfin- .tion and;

Jig. 2 is. a series .of ncrahhs -fillustrating the .operationotthecirciiitiof'l ligd.

l'lurning. tofEigii; 1, :the. ring oscillator. -isfshown .ascomprising.hinetilbesp l %9..-in'olusiile,;eaclr pro vided with a-cathode oontroh grid and anode.

20 .The...cathodes.. areiinterconnectedlby a. commoncathcdecorinec'tioni l0-.and'. the..anodes areinterconnected over.in'dividuaLanQde. resistors; I hand .a. .commomanddei .leadij 1 21.150,a source of anode supply 1.1.3 i'IEheanodes. oft each .ofithefltubgs,are

' l inter-connected -W7th'i1the grids0f .ithe. succeedin tubelby. means.or. couplingpcondensersl l 442.41 fclusiveiarid, eachis providedwithanoutputlead i234 Ilinolusive. In series. witl commoncathodeconnection" is provided a current. regulatotcon .stituted by, pentode-tube ,32 ;.-connec,ted., on. one

.side to. ground ,aridthej. other. side tdcthe. common cathodeconnection .'through conductor 33. .A crystal. contrdlled oscillatorisishownrat. 3100mpricing :2. tube 35..arid.the necessary circuits.theresistor'B Grand coupling. condenser. 31. .to. .the grid of.oneehalf. ofiaidual .triode3 8.=.which.seryes.as.an

amplifier. .;,In. the first-anode circuit-of tube-38.-is provideda.0611,39.Ishuntedhvthe, cQndensereAfl which provides...resonant-:oircuitufor sht c ex- ..cita'tion by (the ,.wave received ,from... 3,8.,Iihis rlesonantcircuit. 3.9, an, :is.lshuntedzby-sa --re. tifiier 4LisoLthatonlythefirst .posi-tive peak,;is,- .efiectiye. .FI'his, peak-wave. is applied; overca couplingcon- ;denser'. i2 tothe;inputelectrodezofcthe; other-vitrii odesection-inf. tube- 3.8, the-output .pf which;.;- is

. taken oversaicathode resistonflranditacoupling condenser 44fonapplication torthe-commonweathode conductor flioileriline 3,3.Current gegulator 32 15... biased..that iit .wi1l pass .a. substantiallyconstant. amount N of. .current just 1. sufficient alto ,maint'ainoneof..the tubes-lofnthe xing..-.oscillator conducting. V

I jTurnin'gmomto. Eig.-.,2,...the .explanatlomiflfathe circuit may beused to generate'po'sitive synchro--" operation of the circuit justdescribed wm stant circuits made for the circuit operating as asynchronised pulse generator. Curve A illustrates the pulse output fromtube 38, the pulses being numbered I-9 corresponding to applicable tubenumbering of Fig. 1 Assume initially that tube 9 is conducting asindicated by pulse 45 on curve B of Fig. 2 havingbeen started initiallyby the pulse 9applied to cut-off tube 8 which initiates operation oftube 9. This tube 9 continues to conduct until pulse 1 is applied to thecommon cathode connection Ill. The voltage on the grid of tube i isrepresented by curve dot the graph."

While tube 9 is conducting the grid of tube I becomes more negativebelow the normal cut-01f line value due to the coupling from the anodeof the. device 1 operating as a free-running 0sof tube 9. When positivepulse l' is appliedto the common cathode connection, only tube 9 can becut-off since it is the only'tube that isconw I ducting. This tube isaccordingly cut-off .as

shown by the vertical edge 46, of pulse 45. The

anode of tube 9 therefore becomes more positive and the over-carry ofpositive change produces a positive peak 41 on the grid of tube lsufficient to overcome the blocking of this tube and the added positivecathode potential so that this tube I now starts to conduct, its plateoutput being in the form of curve D of Fig. 2. When pulse No. 2 isapplied to the common cathode connection, tube l is likewise cut-off sothat the next, tube 2 operates, its grid and anode potential followingcurves E and F. This cycle is repeated on around the chain of tubes andcontinues so long as pulses are supplied periodically to the cathodelead. It will thus be seen that in the output channels 23-3l there willappear various output pulses in succession which may be used for anydesired purpose. These pulses have a fixed time duration equal to thetime spacing between the pulses 1-9 of curve A. In this way it will beseen that a distribution of pulses of a constant width or time durationis produced the time duration being determined by the frequency ofoscillator 34 from which the pulses are produced: It will be understoodthat with this type of operation the time constant of the circuitsdeterminedby the coupling condensers-i441 and the accompanying gridresistors 48-55 is such that the time spacing between the pulses is lesswith this normal time constant. I

If oscillator 35 and the pulse producing networks coupled therethroughcondenser 44 are omitted the arrangement will operate as a freerunningoscillator; Thus if We assume tube 9 is conducting, the plate of thistube will become negative. with respect to the plate bias. As tube 9continues to conduct the positive charge in condenser 21 decays, thecathode rapidly goes positive and the condenser 22 provides adifferentiated negative pulse upon the grid of tube I. The positivecathode potential for tube 9 continues to build up and the positivepotential on the grid of tube 9 decays by virtue or its time constantuntil the effective grid-cathode potential causes cut-on. The tube thencuts ofi thereby providing-a positive pulse to the grid oftube l,causing it to conduct until the positive charge of condenser 22 decaysthrough tube I similarly as in the case of condenser 2| for tube 9. Thepulses are substantially rectangular to the action of the currentregulator.

cessive triggering continues on around the chain as explainedpreviously. It will be readily seen that by adjusting the values of thetime conof the tubes controllable output The sucto those skilled in theart.

cillator. Moreover, as described above the freerunning oscillator may bearranged to bereadily synchronised by application of a pulse from someexternal source. A

While" the principles of this invention have been described inconnection with a specific embodiment it will be clearly understood thatthis is given merely by way of example. Many variations of the circuitwill present themselves The principal essential of the invention is theprovision of a currentregulator source in series with the ring typeoscillator so thatonly one of the tubes therein may be operatedat atime. The use of the common cathode connection for the purpose oftriggeringorsynchronising the system is also an important subsidiaryfeature of this invention.

While I have described above the principles or" my invention inconnection with specific apparatus, it is to be clearly understood thatthis description is made only by way of example and not as a limitationof the scope of my invention.

What I claim is:

1. A circuit for producing in sequence over a series of output terminalspulses of substantially equal duration, comprising a series of electrondischarge devices each having anode, cathode and grid electrodes, commonanode and cathode supply circuits, resistance and capacitive elementsfor coupling the anode of each tube to the respective grids otthesucceeding tube, an output terminal for each tube, and a constantcurrent regulator adjusted to supply only sufficient current to saidcommon supply circuits to maintain discharge of only one of saiddevices.

2. A circuit according to claim 1, further comprising means forsupplying positive synchronizing pulses to said common cathode circuit.

3. A circuit according to claim 2, wherein said means for supplyingpositive synchronizing pulses comprises a source of positive pulses of agiven 7 periodicity.

4. A circuit according to claim 3, wherein said source of signalscomprise a constant frequency oscillator and shaping means for shapingthe output waves of said oscillator to produce accurately timed pulses.

' 5. A circuit according to claim 4, wherein said shaping meanscomprises, a limiter to produce substantiallysquare waves, a shockexcitable circui-t shunted by a rectifier to produce pulsescorresponding to the leading edge of each square wave oscillation, and acathode follower coupler to apply said produced'pulses to said commoncathode circuit.

6. A circuit for producing in sequence over a series of n' outputterminals an n number of pulses,- comprising a series of n electrondis-charge devices each having an anode, a cathode and a grid electrode,a common anode supply lead coupled over individual anode load resistorsto each of sai-d anodes; a common cathode connection connected to allsaid cathodes, a coupling condenser connected to couple each anode torespective succeeding grid electrode, individual resistors connectingeach grid to a common bias source, the time constants of each condenserresistor combination having a given value, n output terminals and aconstant current regulator tube coupled in series with said commoncathode connection and the anode supply source of said tubes, saidconstant current regulator being adjusted to supply sufficient currentto maintain only one of said electron discharge tubes in operation.

7. A circuit according to claim 6, further comprising a stableoscillator operating at a frequency such that each cycle is slightlyshorter than the period determined by said time constant, means forshaping the output waves from said oscillator to provide positive pulsesregularly spaced at one cycle intervals of said output waves, and meansfor supplying said positive pulses to said common cathode connectionwhereby said electron discharge devices will be sequentially operatedfor a period the duration of which is equal to the spacing of saidpositive pulses.

HARRIS GALLAY.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,373,437 Vanderlyn et a1. Apr. 10, 1945 2,404,918 OverbeckJuly 30, 1946 2,457,819 Hoeppner Jan. 4, 1949 2,512,984 Trousdale June27, 1950

